Optical network unit and power reduction method therefor

Abstract

An optical network unit (ONU) includes a media access control (MAC) circuit, a control circuit, and an optical element. The MAC circuit is configured to output upstream data and transmission time information. The transmission time information includes starting times and ending times of the upstream data. The control circuit is configured to receive the transmission time information and laser guard time information, start outputting laser diode (LD) driving signal a period before the starting time of the upstream data, and determine whether to stop outputting the LD driving signal after the ending time of the upstream data before the starting time of the next upstream data. The optical element is configured to output an output signal based on the upstream data and the LD driving signal. A power reduction method for an ONU is also provided.

What is claimed is: 
     
         1 . An optical network unit (ONU) comprising:
 a media access control (MAC) circuit configured to output a first upstream data, a second upstream data, and a transmission time information, wherein the transmission time information comprises a starting time of the first upstream data, an ending time of the first upstream data, and a starting time of the second upstream data;   a control circuit configured to:
 receive the transmission time information and a laser guard time information; 
 start outputting an laser diode (LD) driving signal a first time period before the starting time of the first upstream data, wherein the first time period is based on the transmission time information and the laser guard time information; and 
 determine whether to stop outputting the LD driving signal based on the laser guard time information and a period between the ending time of the first upstream data and the starting time of the second upstream data; and 
   an optical element configured to receive the first upstream data, the second upstream data, and the LD driving signal and output an output signal based on the first upstream data, the second upstream data, and the LD driving signal.   
     
     
         2 . The optical network unit according to  claim 1 , wherein the laser guard time information comprises a laser on guard time, and the first time period is at least the laser on guard time. 
     
     
         3 . The optical network unit according to  claim 1 , wherein, if the period between the ending time of the first upstream data and the starting time of the second upstream data is greater than or equal to a threshold, the control circuit stops outputting the LD driving signal a second time period after the ending time of the first upstream data. 
     
     
         4 . The optical network unit according to  claim 3 , wherein the laser guard time information comprises a laser on guard time and a laser off guard time, and the threshold is at least the sum of the laser on guard time and the laser off guard time. 
     
     
         5 . The optical network unit according to  claim 1 , wherein, if the period between the ending time of t the first upstream data and the starting time of t the second upstream data is less than a threshold, the control circuit does not stop outputting the LD driving signal after the ending time of the first upstream data before the starting time of the second upstream data. 
     
     
         6 . The optical network unit according to  claim 1 , wherein the laser guard time information comprises a laser on guard time and a laser off guard time. 
     
     
         7 . The optical network unit according to  claim 1 , wherein the transmission time information is determined based on a time period when the first upstream data is outputted by the MAC circuit and a time period when the second upstream data is outputted by the MAC circuit. 
     
     
         8 . The optical network unit according to  claim 1 , wherein the transmission time information is determined based on time periods of a burst enable (BEN) signal generated by the MAC circuit. 
     
     
         9 . The optical network unit according to  claim 1 , wherein the control circuit comprises a finite state machine. 
     
     
         10 . The optical network unit according to  claim 1 , wherein the MAC circuit is configured to output a laser diode (LD) power signal to the control circuit, and the control circuit generates the LD driving signal according to the transmission time information, the laser guard time information, and the LD power signal. 
     
     
         11 . The optical network unit according to  claim 1 , wherein the MAC circuit is configured to output a burst enable (BEN) signal to the optical element. 
     
     
         12 . A power reduction method for an optical network unit (ONU), comprising:
 receiving, by a control circuit, a transmission time information and a laser guard time information, wherein the transmission time information comprises a starting time of the first upstream data, an ending time of the first upstream data, and a starting time of the second upstream data;   starting outputting, by the control circuit, an LD driving signal a first time period before the starting time of the first upstream data, wherein the first time period is based on the transmission time information and the laser guard time information;   determining, by the control circuit, whether to stop outputting the LD driving signal based on the laser guard time information and a period between the ending time of the first upstream data and the starting time of the second upstream data;   receiving, by an optical element, the first upstream data, the second upstream data, and the LD driving signal; and   outputting, by the optical element, an output signal based on the first upstream data, the second upstream data, and the LD driving signal.   
     
     
         13 . The method according to  claim 12 , wherein the laser guard time information comprises a laser on guard time, and the first time period is the laser on guard time. 
     
     
         14 . The method according to  claim 12 , wherein, if the period between the ending time of the first upstream data and the starting time of the second upstream data is greater than or equal to a threshold, the control circuit stops outputting the LD driving signal a second time period after the ending time of the first upstream data, and the second time period is at least the laser off guard time. 
     
     
         15 . The method according to  claim 14 , wherein the laser guard time information comprises a laser on guard time and a laser off guard time, and the threshold is at least the sum of the laser on guard time and the laser off guard time. 
     
     
         16 . The method according to  claim 12 , wherein, if the period between the ending time of the first upstream data and the starting time of the second upstream data is less than a threshold, the control circuit does not stop outputting the LD driving signal after the ending time of the first upstream data before the starting time of the second upstream data. 
     
     
         17 . The method according to  claim 12 , wherein the laser guard time information comprises a laser on guard time and a laser off guard time. 
     
     
         18 . The method according to  claim 12 , wherein the transmission time information is determined based on a time period when the first upstream data is outputted by the MAC circuit and a time period when the second upstream data is outputted by the MAC circuit. 
     
     
         19 . The method according to  claim 12 , wherein the transmission time information is determined based on time periods of a burst enable (BEN) signal generated by the MAC circuit. 
     
     
         20 . An optical network unit (ONU) comprising:
 a media access control (MAC) circuit configured to output a first upstream data, a second upstream data, and a transmission time information, wherein the transmission time information comprises a starting time of the first upstream data, an ending time of the first upstream data, and a starting time of the second upstream data;   a control circuit configured to receive the transmission time information and a laser on guard time and a laser off guard time, and output a laser diode (LD) driving signal according to the transmission time information and the laser on guard time and the laser off guard time;   an optical element, coupled to the MAC circuit and the control circuit, configured to receive the first upstream data, the second upstream data, and the LD driving signal, thereby transmitting the first upstream data and the second upstream data, wherein the optical element is powered on or off according to the LD driving signal.